“Mass spectrometry” is a method which executes detection by ionizing a sample, and separating the ionized molecule according to mass/charge (m/z). Since acidic substances are likely to generate negative ions, and neutral substances are likely to generate positive ions, such ions are respectively measured.
Biopolymers such as nucleic acid, protein, sugar chain and the like are analyzed by conducting multi-stage MS measurement (MSn measurement). In multistage MS measurement, MS measurements are repeatedly conducted in such a manner that a parent ion which is generated at the first stage of MS measurement is chosen as a precursor ion and subjected to the second stage of MS measurement, and a precursor ion is chosen from product ions generated as a result and subjected to the third stage of MS measurement. This multistage MS measurement provides more specific structural information, however, it is necessary to generate abundant precursor ions to conduct the multistage MS measurement.
On the other hand, SUGAHARA, D et al., ANALYTICAL SCIENCE, 19, pp. 167-169 (2003) discloses that oligosaccharide is fluorescent-labeled and subjected to measurement by FP method or ELISA method.
Also, Brown, C. W, et al., Analytical Chemistry, Vol. 54, No. 9, pp. 1472 (1982), and Yasuo Iida et al., BUNSEKI KAGAKU, Vol. 32, pp. 401 (1983) disclose quantification methods regarding absorptiometry.
Further, on the other hand, Niclas G. Karlsson et al., Rapid Communications in Mass Spectrometry, 18, pp. 2282-2292 (2004) reports that structural specificity of MS2 spectrum of neutral sugar is improved by LC-nano-ESI-MS (negative mode measurement).